There’s a clear campaign against the mentally ill with the global rise of fascism. Lots of it shows up in anti homeless rhetoric, but you can see it in the MAHA and anti vaccination movements.
There’s no reason to use the word “r-tarded” to describe someone. As someone who’s worked with the intellectually challenged, it’s an insult to them to compare them with people who are willfully ignorant.
I don’t think anyone is saying that clinical language doesn’t have a use. If anything, it’s the use of these words as general-purpose insults that makes them unfit for clinical use, not the other way around.